The most likely fix on a Jandy AquaPure showing Check Cell: verify actual salinity at a lab before doing anything else. Most Check Cell calls in South Florida are pools that drifted under 2,800 ppm after rain or backwash. Add salt, run a diagnostic. If salt is correct, water is warm, and Check Cell persists, work the path: cell scale, then flow switch, then board. Cell replacement is the last assumption, not the first.
Most common symptoms
- Check Cell lit on the controller despite normal salt readings.
- No Flow warning when the pump is clearly running.
- AquaPure powers up but produces no chlorine.
- Display dim, flickering, or completely dark with line voltage at the unit.
- Cell makes a buzzing or chattering sound when generating.
Diagnostic walkthrough
- Salt at the lab first. The AquaPure's onboard salt reading drifts as the cell ages. A handheld photometer or pool-store reading is the truth. Confirm your model's target range against the Jandy AquaPure manual — current models target a 3,000–4,500 ppm range with a 3,200 ppm sweet spot. Add salt to range first; many Check Cell complaints clear with that alone.
- Water temperature. Most AquaPure controllers stop generating once water drops near 50°F — verify the cold-water cutoff for your specific model in the Jandy manual. Florida pools see this on January cold snaps, especially if the heater is off. Wait for 60°F+ before assuming a fault.
- Inspect the cell. Pull it. Hard scale on the plates looks like white crust. Acid-wash with a 4:1 dilution (four parts water to one part muriatic acid), plates submerged ~10–15 minutes. Always pour acid into water, never water into acid; wear chemical splash goggles, gloves, and long sleeves; work outdoors; and never mix the bath with chlorine products (chlorine gas). Reinstall and run a diagnostic.
- Test the flow switch. The paddle stiffens with age and lime. Pull the switch, work the paddle by hand, look for grit. Jumper the two flow-switch leads at the controller — if the unit now thinks there is flow, you confirmed the switch.
- Open the controller. With power off. Look for visible board damage: scorched relays, swollen capacitors, dead-bug spots. Florida humidity kills these boards faster than the cells.
Step-by-step fix
For low salt: add salt, wait two pump cycles, retest. For scale: acid-wash and reinstall. For a sticky flow switch: clean or replace the paddle assembly — cheap part, common failure. For a board: replace the AquaPure controller; do not attempt component-level repair on a 240V outdoor PCB.
South Florida-specific failure modes
- Hard water scale. Boca, Delray, Coral Springs — high calcium fill. Quarterly cell inspection is realistic, not optional.
- Lightning damage to the PCB. AquaPure controllers near a strike take out the surge-suppression first, then the relays. Whole-pad surge protection helps; a direct hit still wins.
- Salt cell corrosion at the cable terminal. Coastal pools see green oxide build at the cell-to-cable junction within 5 years. Dielectric grease at install slows this.
- Calcium chip-out on aged cells. Repeated acid-washing on a 5-year cell starts pulling the plate coating with the scale. There is a point where you stop washing and start replacing.
When it's time to replace
Cell with 9,000+ hours, multiple acid-washes, and still failing the diagnostic — replace the cell. Controller with a visibly damaged board, intermittent display, or relay chatter — replace the controller. If both are 6+ years old, replace as a system; the labor is the same and you avoid a return visit. See our salt chlorine generators primer for system-level context.
When to call a pro
Anything past salt, temperature, and a basic acid-wash is pro territory. The AquaPure controller carries 240 V on the input side — lock out the breaker before opening it, and consider that pro work either way. The flow switch is a 30-second swap when you know what you are doing and a half-hour fight when you don't. In Florida, residential pool repair work is regulated by the DBPR (RP / CPC license categories). Schedule a pool equipment repair visit for diagnosis and a flat-rate quote.
FAQ
What does Check Cell mean?Salt low, water cold, cell scaled, or cell worn — in that order of likelihood.
How do I test the flow switch? Jumper the two leads at the PCB. If the unit thinks there is flow, the switch is the problem.
How long does the cell last?10,000 hours, typically 4–6 years in Florida.
How do I know the board is bad? Cell tests good, salt is correct, flow is correct, and the unit still does not generate or display reliably.
Can I clean a scaled cell?Yes — 4:1 water-to-muriatic, 10–15 minutes, rinse, reinstall.
Want a pro to handle this?
Our CPO-certified techs run this exact playbook on every weekly service visit.